fix(openai): reject malformed Codex image base64 (#111235)

* fix(openai): reject malformed Codex image base64

* fix(openai): align Codex image base64 trimming

* fix(openai): match Codex base64 decoding

extensions/openai/image-generation-provider.test.ts

@@ -1629,6 +1629,79 @@ describe("openai image generation provider", () => {
     });
   });
 
+  it.each([
+    {
+      name: "invalid alphabet from output item",
+      event: {
+        type: "response.output_item.done",
+        item: { type: "image_generation_call", result: "aGVs!bG8=" },
+      },
+    },
+    {
+      name: "invalid alphabet from completed output",
+      event: {
+        type: "response.completed",
+        response: {
+          output: [{ type: "image_generation_call", result: "aGVs!bG8=" }],
+        },
+      },
+    },
+    {
+      name: "missing canonical padding",
+      event: {
+        type: "response.output_item.done",
+        item: { type: "image_generation_call", result: "aGVsbG8" },
+      },
+    },
+    {
+      name: "internal whitespace",
+      event: {
+        type: "response.output_item.done",
+        item: { type: "image_generation_call", result: "aGVs bG8=" },
+      },
+    },
+    {
+      name: "non-zero trailing bits",
+      event: {
+        type: "response.output_item.done",
+        item: { type: "image_generation_call", result: "Zh==" },
+      },
+    },
+  ])("rejects malformed Codex image base64 from $name events", async ({ event }) => {
+    mockCodexAuthOnly();
+    mockCodexRawStream(`data: ${JSON.stringify(event)}\n\n`);
+
+    const provider = buildOpenAIImageGenerationProvider();
+    await expect(
+      provider.generateImage({
+        provider: "openai",
+        model: "gpt-image-2",
+        prompt: "Draw from malformed image data",
+        cfg: {},
+      }),
+    ).rejects.toThrow("OpenAI Codex image generation returned malformed base64 image data");
+  });
+
+  it("accepts Codex-compatible surrounding Unicode whitespace", async () => {
+    mockCodexAuthOnly();
+    mockCodexRawStream(
+      `data: ${JSON.stringify({
+        type: "response.output_item.done",
+        item: { type: "image_generation_call", result: "\u0085aGVsbG8=\u0085" },
+      })}\n\n`,
+    );
+
+    const provider = buildOpenAIImageGenerationProvider();
+    const result = await provider.generateImage({
+      provider: "openai",
+      model: "gpt-image-2",
+      prompt: "Draw from valid image data",
+      cfg: {},
+    });
+
+    expect(result.images[0]?.buffer).toEqual(Buffer.from("hello"));
+  });
+
   it("honors configured Codex transport overrides for OAuth image generation", async () => {
     mockCodexAuthOnly();
     mockCodexImageStream({ imageData: "codex-image" });

extensions/openai/image-generation-provider.ts

@@ -14,7 +14,7 @@ import {
 import { createSubsystemLogger } from "openclaw/plugin-sdk/logging-core";
 import { resolveClosestSize } from "openclaw/plugin-sdk/media-generation-runtime";
 import { extensionForMime } from "openclaw/plugin-sdk/media-mime";
-import { MAX_IMAGE_BYTES } from "openclaw/plugin-sdk/media-runtime";
+import { canonicalizeBase64, MAX_IMAGE_BYTES } from "openclaw/plugin-sdk/media-runtime";
 import {
   ensureAuthProfileStore,
   hasConfiguredSecretInput,
@@ -66,6 +66,7 @@ const OPENAI_MAX_IMAGE_RESULTS = 4;
 const MAX_CODEX_IMAGE_SSE_BYTES = 64 * 1024 * 1024;
 const MAX_CODEX_IMAGE_SSE_EVENTS = 512;
 const MAX_CODEX_IMAGE_BASE64_CHARS = 64 * 1024 * 1024;
+const STANDARD_BASE64_ALPHABET = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
 const LOG_VALUE_MAX_CHARS = 256;
 const MOCK_OPENAI_PROVIDER_ID = "mock-openai";
 const OPENAI_OUTPUT_FORMATS = ["png", "jpeg", "webp"] as const;
@@ -577,7 +578,22 @@ function decodeCodexImagePayload(payload: string): Buffer {
   if (payload.length > MAX_CODEX_IMAGE_BASE64_CHARS) {
     throw new Error("OpenAI Codex image generation result exceeded size limit");
   }
-  return Buffer.from(payload, "base64");
+  // Rust's str::trim follows Unicode White_Space (including U+0085), while
+  // JavaScript's trim does not. Match Codex before enforcing canonical Base64.
+  const trimmedPayload = payload.replace(/^\p{White_Space}+|\p{White_Space}+$/gu, "");
+  const canonicalPayload = canonicalizeBase64(trimmedPayload);
+  const padding = canonicalPayload?.endsWith("==") ? 2 : canonicalPayload?.endsWith("=") ? 1 : 0;
+  const trailingBitsMask = padding === 2 ? 0x0f : padding === 1 ? 0x03 : 0;
+  const trailingValue =
+    padding > 0 ? STANDARD_BASE64_ALPHABET.indexOf(canonicalPayload?.at(-(padding + 1)) ?? "") : 0;
+  if (
+    !canonicalPayload ||
+    canonicalPayload !== trimmedPayload ||
+    (trailingValue & trailingBitsMask) !== 0
+  ) {
+    throw new Error("OpenAI Codex image generation returned malformed base64 image data");
+  }
+  return Buffer.from(canonicalPayload, "base64");
 }
 
 function toCodexImage(